As part of semiconductor device processing, a number of integrated circuits (“IC” or “ICs”) are formed on a wafer, or substrate, made from a semiconductive material, such as silicon. Generally, ICs are formed with layers of materials that have semiconductive, conductive, and/or insulative properties. These materials are deposited, doped, etched, or otherwise used to form ICs in individual regions on the wafer that are called die or dies.
After the formation of ICs on the wafer, the wafer can be diced so as to separate individual dies from one another. The separated dies can then be used with larger circuits in either a packaged or an unpackaged form. The wafer dicing process can be accomplished in a variety of ways, including through a scribing, a sawing, or a dicing process.
In scribing, a diamond-tipped scribe is typically used to form shallow scratches in the wafer along pre-formed scribed lines that extend along the spaces (or streets) between the dies and across a surface of the wafer. After scribing, pressure can be applied to the wafer so as to separate or break the dies along the scribed lines. In sawing, a high-speed diamond-tipped saw is often used to cut the wafer along the streets. In a dicing process, grooves are typically formed along the streets in a front surface of the wafer (or the side of the wafer on which the ICs are located) and a back surface of the wafer is removed (e.g., by grinding) until either the grooves are exposed and the wafer is diced or until the wafer is thin enough that it can be separated by the application of pressure.
However, these dicing processes typically have several shortcomings. For example, chips and gouges are often formed along the edges of dies that are separated by scribing or sawing. Similarly, scribing and sawing may cause cracks to form and propagate from the edges of the dies into the substrate so as to render the substrate inoperable and thereby reduce the die yield. To prevent the damage caused by cracking or chipping from spreading to one or more ICs, additional spacing may be required between the dies. Likewise, because some saw blades can be relatively wide, even more spacing may be required between dies on wafers that are diced by sawing. This additional space between dies can result in wasted wafer space and a lower number of dies produced from each wafer.
Additionally, some dicing processes may have shortcomings when used with wafers that have metal deposited on their back surfaces (back surface metallization). For example, the dicing process may leave the sidewalls of the individual dies exposed during the metallization process. Accordingly, metal may be allowed to be deposit on the sidewalls of the die, causing the die to short circuit during use. Moreover, the removal of an individual die from a diced wafer with back surface metallization may cause the metal on the back surface of one or more adjacent dies to be peeled away from the adjacent dies.